Chemically Reversible Four-Electron Oxidation and Reduction Utilizing Two Inorganic Functional Groups

Four-electron oxidation of the quadruply bonded W2(II,II) compound W2(2,2′-dipyridylamide)4, 1, results in the formation of a novel, diamagnetic ditungsten terminal oxo compound [W2O(2,2′-dipyridylamide)4]2+, 2. In contrast to the chemical inertness of mononuclear tungsten oxo species, 2 undergoes a four-electron reduction including oxygen-atom transfer in reactions with excess tri-tert-butylphosphine in acetonitrile to recover 1. This unusual chemically reversible multielectron reactivity is ascribed to the cooperation of W−O and W−W multiple bonding.